Dr Sam Holford showing an MRI scan

Uterine Anomaly and ACUM Resection

Uterine anomalies are congenital (present from birth) differences in the shape or structure of the uterus. These can impact fertility, menstruation, and sometimes cause pain or complications in pregnancy.

One particular type of anomaly that’s gaining increased recognition is the ACUM – an Accessory Cavitated Uterine Mass – which can cause severe pain and heavy bleeding in younger people and is often underdiagnosed.

I offer detailed assessment and minimally invasive surgery to help identify and correct these issues when appropriate.

What are uterine anomalies?

The uterus forms during early fetal development from two tubes (Müllerian ducts) that fuse and remodel into a single cavity. If this process doesn’t go as planned, structural differences can result. These include:

  • Septate uterus: a fibrous/muscular wall dividing the uterine cavity
  • Arcuate uterus: a mild indentation – usually normal variant
  • Bicornuate or didelphys uterus: partial or complete duplication
  • Unicornuate uterus: half the uterus forms
  • ACUM: a small mass within or adjacent to the uterus with a cavity, often mistaken for a fibroid or endometriosis
Accessory Cavitated Uterine Mass
An Accessory Cavitated Uterine Mass (ACUM) is a rare birth defect where a small, separate cavity lined with functional uterine tissue develops within the muscle wall of an otherwise normal uterus. Because this accessory cavity has no exit, menstrual blood gets trapped and accumulates, typically causing severe, recurring pelvic pain and menstrual cramps in young women that often don't respond to typical pain medication. The definitive treatment for ACUM is surgical removal of the mass. Diagram from https://doi.org/10.1111/aogs.14801.

When should uterine anomalies be treated?

Many anomalies don’t need treatment, but surgical correction can help when symptoms or complications arise, such as:

  • Recurrent miscarriage or infertility
  • Severe dysmenorrhoea (period pain)
  • Irregular bleeding
  • Pain with periods despite hormonal treatment
  • ACUM with severe one-sided pain in adolescents or young adults

What is ACUM?

Accessory Cavitated Uterine Mass (ACUM) is a non-communicating cavity lined with endometrium, often embedded in the uterus or adjacent to the round ligament. It:

  • Is often present from early teens
  • May mimic endometriosis or fibroid on ultrasound
  • Causes severe cramping, especially on one side
  • Doesn’t respond well to standard hormonal treatments

Surgical excision is often curative and can dramatically improve quality of life.

Diagnostic approach

I use high-resolution transvaginal ultrasound to assess uterine anatomy and plan surgery. MRI is also often utilised for less common anomalies such as ACUM.

Surgical options

Hysteroscopic Septum Resection

  • Performed entirely via the vagina with a small camera (no cuts)
  • Divides a fibrous or muscular septum to create a single cavity
  • Day procedure with rapid recovery
  • Improves fertility outcomes and reduces miscarriage risk

Laparoscopic ACUM Resection

  • Keyhole surgery to remove the mass
  • Preserves normal uterus and ovaries
  • Excellent outcomes for pain relief
  • Performed under general anaesthesia with 1–2 week recovery

What to expect

  • Day surgery or 1-night stay
  • Minimal scarring (2–4 small incisions for laparoscopic surgery)
  • Some bleeding, cramping, or bloating for a few days
  • Most patients return to work in 1–2 weeks (or sooner for hysteroscopic-only cases)
  • You may be asked to avoid pregnancy for a few months post-surgery depending on the repair

Fertility and reproductive outcomes

  • Septum resection has been shown to reduce miscarriage risk and improve live birth rates in selected patients
  • ACUM resection can improve symptoms and allow for normal uterine implantation
  • If your anomaly may impact pregnancy or delivery, I’ll discuss possible considerations with you ahead of time
Dr Sam Holford

Is surgery for you?

ACUM is a rare uterine anomaly causing severe period pain. As an Auckland specialist, I perform advanced laparoscopic resection to remove the mass and relieve pain.

Book an appointment

FAQs

How do I know if I have a uterine anomaly?
Many people with uterine anomalies have no symptoms. They are often discovered during an investigation for recurrent miscarriage, infertility, or severe period pain that doesn’t respond to usual treatments. A detailed 3D ultrasound or an MRI scan is the best way to make a diagnosis.
Will surgery to correct a uterine anomaly improve my fertility?
For certain anomalies, like a uterine septum, surgery can significantly reduce the risk of miscarriage and improve the chances of a successful pregnancy. The goal is to create a more supportive uterine environment for an embryo to implant and grow.
What is an ACUM and why does it cause so much pain?
An ACUM is a small, separate uterine cavity that is not connected to the main uterus. It has its own lining that bleeds during a period, but the blood gets trapped. This build-up of blood causes severe, cyclical, one-sided pain, often starting in the teenage years.
What is the recovery like after surgery for a uterine anomaly?
Recovery depends on the type of surgery. For a hysteroscopic septum resection (done through the vagina with no cuts), you can often return to normal activities in a day or two. For a laparoscopic ACUM resection (keyhole surgery), recovery usually takes 1-2 weeks.
If I have a uterine anomaly, will I need a caesarean section for future pregnancies?
Not always, but it is more likely. It depends on the type of anomaly and the surgical repair performed. If the uterine muscle has been significantly incised and repaired, a planned caesarean section is often recommended for safety in future deliveries. We would discuss this in detail.

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Please note: This information is general in nature and not a substitute for medical advice tailored to your specific situation.